We are south of the border and in from the sea, underground and staring up at the light. Narrow shafts of sunlight breach the subterranean dark via a constellation of tiny skylights that are, our host points out, actually repurposed eyeglass lenses. The arched ceiling itself is fashioned from the upturned hull of an old wooden fishing boat, burned black. The walls of the oblong space are simply a cutaway of packed, tan earth. It is kind of the best room in or under the world, or as Phil Gregory puts it, proudly: “My future mad-scientist laboratory.”

Phil Gregory — impish, 60-ish, trim beard and wavy silver hair tucked behind his ears — is a winemaker, innkeeper and aspirational scientist, though he didn’t used to be any of these things. Originally from Manchester, England, he spent most of his career in the music industry in Los Angeles. He and his wife, Eileen, who’d started a healthy-living cable channel in Europe with Dave Stewart of Eurythmics, spent years vacationing up and down the Baja California peninsula. When a friend suggested they drive the bumpy two-lane road up to see the rock-strewn landscape of a small wine-producing area called Valle de Guadalupe, they’d never heard of the place. They weren’t alone.

Vines have been planted and wine made on the peninsula since the 17th century, first by Spanish missionaries, then by Russian Molokans, then by faceless corporate factories squeezing faceless corporate wine out of cheap land with little thought given to the terroir of one of the oldest vineyards of the New World. To put it bluntly, on hearing the word “Mexico,” we don’t, most of us, answer immediately: “Wine country!” But here it is, an hour an a half south of San Diego, skirting Tijuana down the misty curving beauty of Highway 1, then a quick turn inland: a wild and beautiful wine land, lush in the valleys, dry in the hills and dotted with mini-boulders that give the terrain a distinctive Napa-meets-Mars quality.

It was the sight of those rocks that did it for the Gregorys. They purchased some land as a weekend retreat, 70 unfenced acres where Eileen could ride her horse and Phil could learn to make a little wine for their private amusement. Things did not go as planned. “The difference in our plans was that mine involved lying in a hammock with a beer and Eileen’s involved this,” Phil says, swinging a hand in the air to indicate his winery as well as La Villa del Valle, their lovely six-room inn. “So we compromised and did this.”

This grew over the years to embrace olive-oil production, a line of lavender soaps and candles made by Eileen and a restaurant, Corazón de Tierra, which is probably the most interesting place to eat in the valley.

The winery is still a work in progress. Workmen are affixing more glass lenses to a wall.

Phil describes his plans for a grand entrance, for a Bandol-style red he’s going to try with some Mourvèdre he recently planted, and a list of esoteric gadgetry he requires for his wine wonk laboratory. ” ‘The NeverEnding Story’ — his favorite movie,” Eileen jokes.

Around the time the Gregorys arrived, others were beginning to see the potential in this sleepy valley. Hugo D’Acosta, a French-trained winemaker from Mexico City, came in the late ’80s, hoping to find a place to make quality Mexican wines. He worked for the big guys for a dozen years before breaking off on his own to found Casa de Piedra and become the face of an independent grower-producer winemaking movement. Hugo, as everyone calls him — pronounced OOOH-go — has been called the Mexican Mondavi.

He is ubiquitous but press shy, soft spoken but rigidly opinionated, and there is something of Steve Jobs in his grown-up hippie-turned-oenologist oligarch, a dreamer who dreamed up an industry and trusts his own instincts. Then there is the Che Guevara aura, the sad-eyed, cat-whiskered revolutionary up in the hills waging his battles against the Man for his constituents of previously disenfranchised farmers. They used to sell their grapes to the big companies for pennies a pound. Then D’Acosta came to town, set up a school and taught them how to make wine. Ten years ago there were only a handful of wineries in the valley. Now there are more than 50.

“Hugo persuaded farmers to grow better grapes,” Phil says, admiringly. “He persuaded the winemakers to make better wine and taught them how to do it. He saw the potential and if it weren’t for him, none of what’s happened here would have come to pass.”

One afternoon, my girlfriend, Evyn, and I arrange to meet D’Acosta at Paralelo, a pretty winery on the grounds of what was once a huge trash dump. Hugo’s brother, Alejandro, an architect, built the concrete structure that houses the winemaking facilities. It is not a warm-and-fuzzy building. Imprinted on its angular walls are outlines of tires and other detritus, a stark tribute to the previous life of the place.

Alejandro also designed Phil’s winery — it was his inspired idea to rescue rotting fishing boats doing time on dry dock and put them to work as the exoskeleton of a new building. His own weekend house in the valley makes use of considerably less romantic raw material: a salvaged truck container, a decommissioned meth lab.

“Don’t tell everyone,” Hugo says when I admit what a happy surprise we’ve found the area to be. “Don’t tell.” He’s mostly kidding (I think).

In any case, the buzz about the valley has been building for a few years, and people now come to taste their way across the valley and fill the restaurants at night. But D’Acosta is nonetheless concerned that progress can come too quickly. Sudden spotlight and attention can wrong-foot an industry that is, despite four centuries of vinous prehistory, really just finding its way.

“A million years ago all of this was on the ocean floor,” D’Acosta says. Over the ages the peninsula rose and fell as it broke away from the mainland, leaving the interior soil with a sandy salinity that, along with the breezy Mediterranean weather, contributes to the special quality of valley wines. Describing terroir is a tricky business. How do you define the specific identity of the wines grown here?

“Mexican,” D’Acosta answers, without hesitation. “People say, ‘Why don’t you grow one specific grape, like the Argentines or Uruguayans?’ The answer is Mexico is like that. Mexico is a mosaic of cultures. Which is the true

Mexican food? Nobody knows. . . . We need to brand Mexico as Mexico is. We are a very complicated, mixed culture. I think it would be a mistake to try to simplify.”

People will continue to make what they mean to be complimentary comparisons between this valley-on-the-cusp and the memory of Napa-as-it-once-was. But the true appeal of this place is its particular character and not how it conforms to some picture-book idea of what a sun-dappled wine paradise should look like.

Afternoons, the sun feels brutally close. Nights, comets and stars crash and sputter in plain view above the suddenly cold earth. One night we were driving home from dinner over a dirt road and nearly smushed a spider the size and hairiness of a small cocker spaniel. “The valley is a magical place,” Eileen Gregory says in her quietly animated way. “Magic” is a word that comes up often among transplants and locals.

“It’s this incredible conurbation of country people who never left, cowboys who ride horses without a saddle and live off the land and, because it’s a wine region, there are a lot of sophisticated, well-traveled people,”

Eileen says.

The key to cashing in on the attention is to build for the latter types the kinds of things they require (hotel rooms with Wi-Fi, thoughtful food) without driving away the former and turning the place into another anodyne anywhere, bleached of the culture that made it interesting in the first place.

The hotel we’re staying at is a fine and mostly successful attempt to fuse these two worlds. It’s called Endémico, and there’s a good chance you heard about it — and saw pictures of its pitched-roofed rooms perched amid the boulders at cloud level — before you even knew of Valle de Guadalupe. The hotel is owned by Grupo Habita, and it’s the kind of design-conscious, eco-messaging operation that everyone in town tells you couldn’t have existed here five years ago. Each of the 20 pod-rooms, reached by dusty walkway, is composed of glass and Cor-Ten steel and floats high above the valley — great for the views, not so great when you have to walkie-talkie back to reception and wait for a Polaris 4×4 Ranger to collect you every time you want to go to your car. But the rooms sit lightly on the land and you do feel like you are in the rocky terrain, not just looking out at it.

The main road through Valle de Guadalupe and the area of Ruta del Vino is Highway 3. Addresses are given in kilometer-marker numbers along it. From there, you depart the asphalt and leave a cloud of dust behind as you. Over lunch at her restaurant, Corazón de Tierra, Eileen tells me something she says Hugo D’Acosta likes to say: “Bad roads, good tourists. Good roads, bad tourists.”

For now the spirit of the valley seems to have survived the incursion of a smooth-paved central highway. At any rate, I can’t get misty eyed about the lost innocence of more rustic times when the chef Diego Hernández has just sent out a smart little snack of local sea urchin affixed to a crunchy square of chicharrón with a dab of puréed avocado. Next, a near-perfect dish of fleshy roasted escolar dusted with the ashes of burnt onion, seaweed and a smoky parsnip purée. “To remember the Mayan tradition of cooking with smoke and wood flavors,” the server says. We’re drinking Phil’s spicy 2010 Tempranillo, nicely chilled. He provides the house wine at Pujol, a Mexico City restaurant that recently landed at No. 36 on the influential World’s 50 Best Restaurants — testament both to the seriousness of the man’s hobby and the respect the wines of the region are finally getting at home.

Casa de Piedra (kilometer marker 93.5) is Hugo D’Acosta’s original winery, ground zero of the revolution. Here there is no modernist structure, just a sweet old stone house that’s been expanded over the years. We’re drinking with Víctor Moreno, D’Acosta’s young lieutenant and winemaker, and Drew Deckman, a laid-back American chef. Moreno uncorks some sparkling wine, which it seems impolite to spit, and then a bottle called Contraste Intercontinental, a blend of grapes from D’Acosta’s Languedoc-Roussillon winery with those from Casa de Piedra. “It’s a friendship wine,” Moreno says of the intercontinental experiment. “Imagine the French thinking about this French wine made by Mexican people!”

Next we try . . . well, next we try a dozen different things. It’s hot in the shade and what’s being poured is, like those French and Mexican juices, getting a bit mixed up. The talk turns — as wine talk should — to food. No matter how pleasing the product, tasting-room marathons tend to get a little dull after the first half dozen sips. Swirl, nose, suck, chew, spit, repeat — time for lunch. An enduring conundrum about visiting wineries: they all start to look the same after the second day.

The local answer to the riddle of how best to enjoy a day in wine country is known as the asador campestre, or country grill. Typically these are casual restaurants on the grounds of wineries. You’re in the midst of the vines, but instead of being stuck inside talking malolactic fermentation, you’re outside at a table in the sun, plucking bottles out of ice and eating well.

Deckman’s en el Mogor is Drew Deckman’s summer escape from his more formal restaurant down the coast in San José del Cabo, his very own outdoor laboratory on the grounds of Mogor-Badan winery. “I feel different here,” he says. “I’m on vacation.” Which is not to say he isn’t working. He’s running around, fanning the wood fire grill, pulling pints of the house beer he makes flavored with fennel and orange flowers from the property, bringing a visitor across a field to point out the pink peppercorn plants and the carob trees he uses to make ice cream.

Pepita the rescue dog and Guapo the slobbering stray circle the tables. The food is improvisational, brightly seasoned, not in the least Mexican but a freewheeling exploration of its flavors: an unlikely surf and turf of beef tongue carpaccio with gooseneck barnacles; plates of oysters and roasted sardines; grilled local abalone with charred summer corn.

“Everybody talks about farm to table — well, we just took the table to the farm,” Deckman says.

A large table of winemakers and their families shows up. Deckman turns the volume up on the Blue Note jazz, uncorks a few more bottles of Mogor-Badan estate-chilled Chasselas and gets back to the grill. He couldn’t look any happier.

ESSENTIALS: VALLE DE GUADALUPE, MEXICO

Hotels Endémico Grupo • Habita’s new eco-conscious hotel has modern pod-like glass and steel huts with unparalleled views of the valley. Carretera Tecate-Ensenada, Highway 3 at Km 75.La Villa del Valle • With a pool and the best new restaurant in town on the property, why would you need to leave this lovely six-room inn? Carretera Tecate-Ensenada, Highway 3 at Km 88; 011-52-1-646-183-9249.